Sturgeon's top moments

Scotland's First Minister Nicola Sturgeon in pictures.

But a Health Protection Scotland study found "sufficient" evidence that cancer-causing dust crystalline silica occurred at levels which would pose a risk to workers.

Labour, Lib Dems and Greens argued the research demonstrated that fracking should be completely banned, with the potential dangers outweighing the benefits.

But Scottish Tory Energy spokesman Alexander Burnett hit out at "another missed opportunity" adding: "We have more dithering and delay and a failure to recognise an opportunity to boost the economy and create jobs at a time when the North Sea oil and gas industry is in decline."